Sharing container images between mulitple hosts through container orchestration

ABSTRACT

A computer-implemented method is provided for container sharing and scheduling in an environment having a plurality of nodes. The method includes deploying a container management service system that manages a list of layered images. The list specifies one or more container attributes for each layered image stored at the nodes. The method includes selecting, by a processor-based scheduler of the container management system based on the list of layered images, a given one of the nodes which (i) includes image layers residing in a container and (ii) communicates with one or more candidate nodes that include one or more missing image layers. The candidate nodes are determined from among the nodes based on one or more availability criterion. The method includes pulling the one or more missing image layers from the candidate nodes and copying the one or more missing image layers to the given one of the nodes.

BACKGROUND Technical Field

The present invention relates generally to information processing and,in particular, to sharing multiple container images between multiplehosts through container orchestration.

Description of the Related Art

Container-based virtualization (e.g. Docker®) is widely used in Cloudand DevOps environments. There are many technologies in container-basedvirtualization (LXC, namespace, cgroups, UnionFS, and so forth), butUnionFS is one of important functionality that enables us to combinemultiple read-only file system vertically. Each UnionFS layer has uniquecontent hash ID (e.g., d31f33e . . . ), so it guarantees the imagelayer's immutability.

Container management systems (e.g. Kubernetes®, Docker® Swarm) aredeveloped for managing container lifecycle (Create, Read, Update, andDelete (CRUD)) in a cluster-wide system. As a typical example, once acontainer creation request is received, a scheduler decides the hostwhere requested containers will run, and then an agent in the hostlaunches the container.

However, the container management systems are not without deficiency.For example, all hosts download “images” from a centralized containerrepository when launching a new container. Thus, fetching imagesindependently from the repository even if these are same UnionFS layer,so that network bandwidth is consumed by the duplicated image downloadtasks. Moreover, the reliability of network reachability to therepository will be a single point of failure.

Further relating to deficiencies of such container management systems,the container scheduler does not consider the locality where these imagelayers are stored or not stored. The image layer is immutable andsharable, but the system does not manage it. Moreover, container imagesare deleted periodically if the host does not have enough space to keepthe container images.

Thus, there is a need for a mechanism to share container images betweenmultiple hosts.

SUMMARY

According to an aspect of the present invention, a computer-implementedmethod is provided for container sharing and scheduling in anenvironment having a plurality of nodes. The method includes deploying acontainer management service system that manages a list of layeredimages. The list of layered images specifies one or more containerattributes for each of the layered images stored at the plurality ofnodes. The method further includes selecting, by a processor-basedscheduler of the container management system based on the list oflayered images, a given one of the plurality of nodes which (i) includesimage layers residing in a container and (ii) communicates with one ormore candidate nodes that include one or more missing image layers. Theone or more candidate nodes are determined from among the plurality ofnodes based on one or more availability criterion. The method alsoincludes pulling the one or more missing image layers from the one ormore candidate nodes and copying the one or more missing image layers tothe given one of the plurality of nodes.

According to another aspect of the present invention, a computer programproduct is provided for container sharing and scheduling in anenvironment having a plurality of nodes. The computer program productincludes a non-transitory computer readable storage medium havingprogram instructions embodied therewith. The program instructions areexecutable by a computer to cause the computer to perform a method. Themethod includes deploying a container management service system thatmanages a list of layered images. The list of layered images specifiesone or more container attributes for each of the layered images storedat the plurality of nodes. The method further includes selecting, by aprocessor-based scheduler of the container management system based onthe list of layered images, a given one of the plurality of nodes which(i) includes image layers residing in a container and (ii) communicateswith one or more candidate nodes that include one or more missing imagelayers. The one or more candidate nodes are determined from among theplurality of nodes based on one or more availability criterion. Themethod also includes pulling the one or more missing image layers fromthe one or more candidate nodes and copying the one or more missingimage layers to the given one of the plurality of nodes.

According to still another aspect of the present invention, a system isprovided for container sharing and scheduling in an environment having aplurality of nodes. The system includes a container management servicesystem. The container management service system is configured to managea list of layered images. The list of layered images specifies one ormore container attributes for each of the layered images stored at theplurality of nodes. The container management service system is furtherconfigured to select, based on the list of layered images, a given oneof the plurality of nodes which (i) includes image layers residing in acontainer and (ii) communicates with one or more candidate nodes thatinclude one or more missing image layers. The one or more candidatenodes are determined from among the plurality of nodes based on one ormore availability criterion. The container management service system isalso configured to allow pulling the one or more missing image layersfrom the one or more candidate nodes and copying the one or more missingimage layers to the given one of the plurality of nodes.

These and other features and advantages will become apparent from thefollowing detailed description of illustrative embodiments thereof,which is to be read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The following description will provide details of preferred embodimentswith reference to the following figures wherein:

FIG. 1 shows an exemplary processing system to which the inventionprinciples may be applied, in accordance with an embodiment of thepresent invention;

FIG. 2 shows an exemplary method for sharing container images betweenmultiple hosts through container orchestration, in accordance with anembodiment of the present invention;

FIGS. 3-4 show an exemplary method for preparing a CLM registry servicein a container management system, in accordance with an embodiment ofthe present invention;

FIG. 5 shows an exemplary environment to which the method of FIGS. 3-4can be applied, in accordance with an embodiment of the presentinvention;

FIG. 6 shows an exemplary method for providing a container schedulingpolicy based on the CLM registry service, in accordance with anembodiment of the present invention;

FIG. 7 shows an exemplary environment to which the method of FIG. 6 canbe applied, in accordance with an embodiment of the present invention;

FIG. 8 shows an exemplary method for pulling cached image layers fromnearby nodes to the scheduled node based on the scheduling policy, inaccordance with an embodiment of the present invention;

FIG. 9 shows an exemplary environment to which the method of FIG. 8 canbe applied, in accordance with an embodiment of the present invention;

FIG. 10 shows a cloud computing environment, in accordance with anembodiment of the present invention; and

FIG. 11 shows abstraction model layers, in accordance with an embodimentof the present invention.

DETAILED DESCRIPTION

The present invention is directed to sharing multiple container imagesbetween multiple hosts through container orchestration.

The present invention has optimized container scheduling and hasprovided a sharing feature based on container lifecycle management inthe cloud.

In an embodiment, the present invention provides a method/system forpreparing a CLuster Membership (CLM) registry service in a containermanagement system, a method/system for providing a container schedulingpolicy based on the CLM registry service, and a method/system forpulling cached image layers from nearby nodes to the scheduled nodebased on the scheduling policy. It is to be appreciated that the terms“host” and “node” are used interchangeably herein to refer to a hardwareapparatus or hardware system involving, at the least, a processor, amemory, and a communication mechanism for interacting with otherhosts/nodes.

Regarding the method/mechanism for preparing a CLM registry service, alist is maintained by the CLM registry service 331, where the listincludes container attributes. The container attributes can include, butare not limited to, image layer id, images id owned by nodes, nodedistance, and so forth. The list is updated responsive to the launch ofa new container or the performance of an image garbage collection cycle.

Regarding the method/mechanism for providing a container schedulingpolicy, the method/mechanism selects a node which has many (e.g., abovea threshold) image layers in a given container, and selects a node withmany candidate nodes nearby that have missing image layers.

Regarding the method/mechanism for pulling cached image layers, themethod/mechanism asks a container management service to get theavailability of candidate nodes (e.g., central processing unit (CPU),network, or distance). Based on the availability, the method/mechanismchooses a node to send a pull request to and copies the missing image toa local node.

FIG. 1 shows an exemplary processing system 100 to which the inventionprinciples may be applied, in accordance with an embodiment of thepresent invention. The processing system 100 includes at least oneprocessor (CPU) 104 operatively coupled to other components via a systembus 102. A cache 106, a Read Only Memory (ROM) 108, a Random AccessMemory (RAM) 110, an input/output (I/O) adapter 120, a sound adapter130, a network adapter 140, a user interface adapter 150, and a displayadapter 160, are operatively coupled to the system bus 102.

A first storage device 122 and a second storage device 124 areoperatively coupled to system bus 102 by the I/O adapter 120. Thestorage devices 122 and 124 can be any of a disk storage device (e.g., amagnetic or optical disk storage device), a solid state magnetic device,and so forth. The storage devices 122 and 124 can be the same type ofstorage device or different types of storage devices.

A speaker 132 is operatively coupled to system bus 102 by the soundadapter 130. A transceiver 142 is operatively coupled to system bus 102by network adapter 140. A display device 162 is operatively coupled tosystem bus 102 by display adapter 160.

A first user input device 152, a second user input device 154, and athird user input device 156 are operatively coupled to system bus 102 byuser interface adapter 150. The user input devices 152, 154, and 156 canbe any of a keyboard, a mouse, a keypad, an image capture device, amotion sensing device, a microphone, a device incorporating thefunctionality of at least two of the preceding devices, and so forth. Ofcourse, other types of input devices can also be used, while maintainingthe spirit of the present invention. The user input devices 152, 154,and 156 can be the same type of user input device or different types ofuser input devices. The user input devices 152, 154, and 156 are used toinput and output information to and from system 100.

Of course, the processing system 100 may also include other elements(not shown), as readily contemplated by one of skill in the art, as wellas omit certain elements. For example, various other input devicesand/or output devices can be included in processing system 100,depending upon the particular implementation of the same, as readilyunderstood by one of ordinary skill in the art. For example, varioustypes of wireless and/or wired input and/or output devices can be used.Moreover, additional processors, controllers, memories, and so forth, invarious configurations can also be utilized as readily appreciated byone of ordinary skill in the art. These and other variations of theprocessing system 100 are readily contemplated by one of ordinary skillin the art given the teachings of the present invention provided herein.

Moreover, it is to be appreciated that environments 500, 700, 900, and1000 described below with respect to FIGS. 5, 7, 9, and 10,respectively, are environments for implementing respective embodimentsof the present invention. Part or all of processing system 100 may beimplemented in one or more of the elements of environments 500, 700,900, and 1000.

Further, it is to be appreciated that processing system 100 may performat least part of the methods described herein including, for example, atleast part of method 200 of FIG. 2 and/or at least part of method 300 ofFIGS. 3-4 and/or at least part of method 600 of FIG. 6 and/or at leastpart of method 800 of FIG. 8. Similarly, part or all of environments500, 700, 900, and 1000 may be used to perform at least part of method200 of FIG. 2 and/or at least part of method 300 of FIGS. 3-4 and/or atleast part of method 600 of FIG. 6 and/or at least part of method 800 ofFIG. 8.

FIG. 2 shows an exemplary method 200 for sharing container imagesbetween multiple hosts through container orchestration, in accordancewith an embodiment of the present invention. Method 200 includes steps205, 210, and 215. Step 205 is described in further detail with respectto FIGS. 3-5. Step 210 is described in further detail with respect toFIGS. 6 and 7. Step 215 is described in further detail with respect toFIGS. 8 and 9.

At step 205, prepare a CLM registry service in a container managementsystem.

At step 210, provide a container scheduling policy based on the CLMregistry service.

At step 215, pull cached image layers from nearby nodes to the schedulednode based on the scheduling policy.

FIGS. 3-4 show an exemplary method 300 for preparing a CLM registryservice in a container management system, in accordance with anembodiment of the present invention. FIG. 5 shows an exemplaryenvironment 500 to which the method 300 of FIGS. 3-4 can be applied, inaccordance with an embodiment of the present invention.

The method 300 and environment 500 relate to step 205 of method 200 ofFIG. 2.

Referring to FIG. 5, the environment 500 involves a host A 510, a host B520, an image repository 530, and a container orchestration system 540.

The host A 510 includes an agent 511 and a Docker® component (e.g., acontainer) 512. The Docker® component 512 maintains an image list 513 ofthe images on host A 510. The image list 513 includes unique contenthash IDs for each of the images on host A 510.

The host B 520 includes an agent 521 and a Docker® component (e.g., acontainer) 522. The Docker® component 522 maintains an image list 523 ofthe images on host B 520. The image list 523 includes unique contenthash IDs for each of the images on host B 520.

The image repository 530 stores images that can be downloaded by thehost A 510 and the host B 520.

The container orchestration system 540 manages the sharing of containerimages between the multiple hosts through container orchestration. Thecontainer orchestration system 540 includes a CLuster Membership (CLM)service 541.

The CLM SVC 541 maintains a list 542 (also referred to as “downloadedimages list”) of images downloaded by the host A 510 and the host B 520.The list 542 includes container attributes. The container attributes caninclude, but are not limited to, image layer id, images id owned bynodes, node distance, and so forth.

Referring to FIGS. 3 and 5, at step 305, send, by host A 505 to theimage repository 530, a request to download images.

At step 310, receive, by the host A 510 from the image repository 530,the requested images and add the unique content hash ID for each of theimages to the image list 513 maintained by the host A 510.

At step 315, register, by the host A 510 with the CLM service 541, theimages downloaded by the host A 510. The images downloaded by the host A510 are registered in the downloaded images list 542 maintained by theCLM service 541.

At step 320, send, by host B 520 to the image repository 530, a requestto download images.

At step 325, receive, by the host B 520 from the image repository 530,the requested images and add the unique content hash ID for each of theimages to the image list 523 maintained by the host B 520.

At step 330, register, by the host B 520 with the CLM service 541, theimages downloaded by the host B 520. The images downloaded by the host B520 are registered in the downloaded images list 542 maintained by theCLM service 541.

At step 335, launch a new container by host A 510.

At step 340, send, by the host A 510 to the CLM service 541, imageinformation for the new container so that the CLM service can update thedownloaded images list 542 maintained by the CLM service 541.

At step 345, perform, by the host B 520, a garbage collection cycle. Thegarbage collection cycle can be performed using, for example, but notlimited to, Least Recently Used (LRU), etc.

At step 350, send, by the host B 520 to the CLM service 541, imageinformation for the garbage collection cycle (e.g., image identifyinginformation for images that have been deleted by the garbage collectioncycle) so that the CLM service can update the downloaded images list 542maintained by the CLM service 541.

FIG. 6 shows an exemplary method 600 for providing a containerscheduling policy based on the CLM registry service, in accordance withan embodiment of the present invention. FIG. 7 shows an exemplaryenvironment 700 to which the method 600 of FIG. 6 can be applied, inaccordance with an embodiment of the present invention.

The method 600 and environment 700 relate to step 210 of method 200 ofFIG. 2.

Referring to FIG. 7, the environment 700 is similar to environment 500,with the inclusion of a container scheduler (interchangeably referred toas “scheduler” in short) 750 and a user device (e.g., a computer) 760.The user device 760 is operated by a user 761. That is, the environmentof the invention (as initially shown in FIG. 5) is shown in furtherdetail to include the preceding elements 750, 760, and 761 relative tostep 210 of method 200 of FIG. 2. The scheduler 750 can be considered tobe part of the container orchestration system 540 of FIG. 5.

Referring to FIGS. 6 and 7, at step 605, receive, by the scheduler 750from the user device 760, a container creation request.

At step 610, check, by the scheduler 750, the CLM service 541 todetermine which image layers are cached (at which nodes/hosts).

At step 615, select, by the scheduler 750, a host from among host A 510and host B 520, based on a set of candidate host selection rules. Thecandidate host selection rules include, for example, selecting acandidate host that has many (e.g., above a threshold) image layers in agiven container and/or selecting a candidate host that has many (other)candidate nodes nearby, where each of the many (other) candidate nodeshave missing image layers.

FIG. 8 shows an exemplary method 800 for pulling cached image layersfrom nearby nodes to the scheduled node based on the scheduling policy,in accordance with an embodiment of the present invention. FIG. 9 showsan exemplary environment 900 to which the method 800 of FIG. 8 can beapplied, in accordance with an embodiment of the present invention.

The method 800 and environment 900 relate to step 215 of method 200 ofFIG. 2.

Referring to FIG. 9, the environment 900 is similar to environment 700,with the inclusion of an additional host C 930. That is, the environmentof the invention (as initially shown in FIG. 5 and further shown in FIG.7) is shown in further detail to include the preceding element 930relative to step 215 of method 200 of FIG. 2. Host C 930 includes anagent 931 and a Docker® component (e.g., a container) 932. The Docker®component maintains an image list 933 of the images on host C 930.

Referring to FIGS. 8 and 9, at step 805, request, by host A 510, thehost management service to obtain the availability of a set candidatenodes to which to send a pull request. The availability can be based on,for example, but not limited to, higher availability of a CentralProcessing Unit (CPU), higher communication/network, or distance).

At step 810, select, by host A 510, a node from among the set ofcandidate nodes to which to send a pull request, based on theavailability.

At step 815, send, from host A 510 to host B 520, a pull request to aselected node (here host B 520) for a set of images.

At step 820, obtain, by host B 520 from host C 930, one or more of theimages in the set and load the one or more images into a localrepository (of host B 520). The one or more images are images specifiedin the pull request, but are not present at host B 520 instead beingpresent at nearby host C 930. The remaining images in the set arealready present at host B 520.

At step 825, download the set of images from host B 520. In this way,the set of images can be obtained from one or more nearby host insteadof a centralized image repository.

Thus, the present invention provides a method and system for sharingcontainer images between multiple hosts through container orchestration.

In cases when the provided external network is narrow or very limited,container launching latency is drastically improved when the presentinvention is used.

In an embodiment, we can use an internal cluster network for gettingcontainer images from other hosts and not from the Internet.

The present invention provides resiliency in that a host can launchcontainers even if the external network is not available.

In an embodiment, the present invention can be used to extend an imagepull rule for pods in Kubernetes®. The rule can use designatorsincluding, but not limited to, the following set: [Always, Never, If NotPresent, Neighbor].

In an embodiment, the present invention can be used to define a servicefor resolving a request involving a neighbor node/host.

It is to be understood that although this disclosure includes a detaileddescription on cloud computing, implementation of the teachings recitedherein are not limited to a cloud computing environment. Rather,embodiments of the present invention are capable of being implemented inconjunction with any other type of computing environment now known orlater developed.

Cloud computing is a model of service delivery for enabling convenient,on-demand network access to a shared pool of configurable computingresources (e.g., networks, network bandwidth, servers, processing,memory, storage, applications, virtual machines, and services) that canbe rapidly provisioned and released with minimal management effort orinteraction with a provider of the service. This cloud model may includeat least five characteristics, at least three service models, and atleast four deployment models.

Characteristics are as Follows:

On-demand self-service: a cloud consumer can unilaterally provisioncomputing capabilities, such as server time and network storage, asneeded automatically without requiring human interaction with theservice's provider.

Broad network access: capabilities are available over a network andaccessed through standard mechanisms that promote use by heterogeneousthin or thick client platforms (e.g., mobile phones, laptops, and PDAs).

Resource pooling: the provider's computing resources are pooled to servemultiple consumers using a multi-tenant model, with different physicaland virtual resources dynamically assigned and reassigned according todemand. There is a sense of location independence in that the consumergenerally has no control or knowledge over the exact location of theprovided resources but may be able to specify location at a higher levelof abstraction (e.g., country, state, or datacenter).

Rapid elasticity: capabilities can be rapidly and elasticallyprovisioned, in some cases automatically, to quickly scale out andrapidly released to quickly scale in. To the consumer, the capabilitiesavailable for provisioning often appear to be unlimited and can bepurchased in any quantity at any time.

Measured service: cloud systems automatically control and optimizeresource use by leveraging a metering capability at some level ofabstraction appropriate to the type of service (e.g., storage,processing, bandwidth, and active user accounts). Resource usage can bemonitored, controlled, and reported, providing transparency for both theprovider and consumer of the utilized service.

Service Models are as Follows:

Software as a Service (SaaS): the capability provided to the consumer isto use the provider's applications running on a cloud infrastructure.The applications are accessible from various client devices through athin client interface such as a web browser (e.g., web-based e-mail).The consumer does not manage or control the underlying cloudinfrastructure including network, servers, operating systems, storage,or even individual application capabilities, with the possible exceptionof limited user-specific application configuration settings.

Platform as a Service (PaaS): the capability provided to the consumer isto deploy onto the cloud infrastructure consumer-created or acquiredapplications created using programming languages and tools supported bythe provider. The consumer does not manage or control the underlyingcloud infrastructure including networks, servers, operating systems, orstorage, but has control over the deployed applications and possiblyapplication hosting environment configurations.

Infrastructure as a Service (IaaS): the capability provided to theconsumer is to provision processing, storage, networks, and otherfundamental computing resources where the consumer is able to deploy andrun arbitrary software, which can include operating systems andapplications. The consumer does not manage or control the underlyingcloud infrastructure but has control over operating systems, storage,deployed applications, and possibly limited control of select networkingcomponents (e.g., host firewalls).

Deployment Models are as Follows:

Private cloud: the cloud infrastructure is operated solely for anorganization. It may be managed by the organization or a third party andmay exist on-premises or off-premises.

Community cloud: the cloud infrastructure is shared by severalorganizations and supports a specific community that has shared concerns(e.g., mission, security requirements, policy, and complianceconsiderations). It may be managed by the organizations or a third partyand may exist on-premises or off-premises.

Public cloud: the cloud infrastructure is made available to the generalpublic or a large industry group and is owned by an organization sellingcloud services.

Hybrid cloud: the cloud infrastructure is a composition of two or moreclouds (private, community, or public) that remain unique entities butare bound together by standardized or proprietary technology thatenables data and application portability (e.g., cloud bursting forload-balancing between clouds).

A cloud computing environment is service oriented with a focus onstatelessness, low coupling, modularity, and semantic interoperability.At the heart of cloud computing is an infrastructure that includes anetwork of interconnected nodes.

Referring now to FIG. 10, illustrative cloud computing environment 1050is depicted. As shown, cloud computing environment 1050 includes one ormore cloud computing nodes 1010 with which local computing devices usedby cloud consumers, such as, for example, personal digital assistant(PDA) or cellular telephone 1054A, desktop computer 1054B, laptopcomputer 1054C, and/or automobile computer system 1054N may communicate.Nodes 1010 may communicate with one another. They may be grouped (notshown) physically or virtually, in one or more networks, such asPrivate, Community, Public, or Hybrid clouds as described hereinabove,or a combination thereof. This allows cloud computing environment 1050to offer infrastructure, platforms and/or software as services for whicha cloud consumer does not need to maintain resources on a localcomputing device. It is understood that the types of computing devices1054A-N shown in FIG. 10 are intended to be illustrative only and thatcomputing nodes 1010 and cloud computing environment 1050 cancommunicate with any type of computerized device over any type ofnetwork and/or network addressable connection (e.g., using a webbrowser).

Referring now to FIG. 11, a set of functional abstraction layersprovided by cloud computing environment 1050 (FIG. 10) is shown. Itshould be understood in advance that the components, layers, andfunctions shown in FIG. 11 are intended to be illustrative only andembodiments of the invention are not limited thereto. As depicted, thefollowing layers and corresponding functions are provided:

Hardware and software layer 1160 includes hardware and softwarecomponents. Examples of hardware components include: mainframes 1161;RISC (Reduced Instruction Set Computer) architecture based servers 1162;servers 1163; blade servers 1164; storage devices 1165; and networks andnetworking components 1166. In some embodiments, software componentsinclude network application server software 1167 and database software1168.

Virtualization layer 1170 provides an abstraction layer from which thefollowing examples of virtual entities may be provided: virtual servers1171; virtual storage 1172; virtual networks 1173, including virtualprivate networks; virtual applications and operating systems 1174; andvirtual clients 1175.

In one example, management layer 1180 may provide the functionsdescribed below. Resource provisioning 1181 provides dynamic procurementof computing resources and other resources that are utilized to performtasks within the cloud computing environment. Metering and Pricing 1182provide cost tracking as resources are utilized within the cloudcomputing environment, and billing or invoicing for consumption of theseresources. In one example, these resources may include applicationsoftware licenses. Security provides identity verification for cloudconsumers and tasks, as well as protection for data and other resources.User portal 1183 provides access to the cloud computing environment forconsumers and system administrators. Service level management 1184provides cloud computing resource allocation and management such thatrequired service levels are met. Service Level Agreement (SLA) planningand fulfillment 1185 provide pre-arrangement for, and procurement of,cloud computing resources for which a future requirement is anticipatedin accordance with an SLA.

Workloads layer 1190 provides examples of functionality for which thecloud computing environment may be utilized. Examples of workloads andfunctions which may be provided from this layer include: mapping andnavigation 1191; software development and lifecycle management 1192;virtual classroom education delivery 1193; data analytics processing1194; transaction processing 1195; and sharing container images betweenmultiple hosts through container orchestration 1196.

The present invention may be a system, a method, and/or a computerprogram product at any possible technical detail level of integration.The computer program product may include a computer readable storagemedium (or media) having computer readable program instructions thereonfor causing a processor to carry out aspects of the present invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as SMALLTALK, C++ or the like, andconventional procedural programming languages, such as the “C”programming language or similar programming languages. The computerreadable program instructions may execute entirely on the user'scomputer, partly on the user's computer, as a stand-alone softwarepackage, partly on the user's computer and partly on a remote computeror entirely on the remote computer or server. In the latter scenario,the remote computer may be connected to the user's computer through anytype of network, including a local area network (LAN) or a wide areanetwork (WAN), or the connection may be made to an external computer(for example, through the Internet using an Internet Service Provider).In some embodiments, electronic circuitry including, for example,programmable logic circuitry, field-programmable gate arrays (FPGA), orprogrammable logic arrays (PLA) may execute the computer readableprogram instructions by utilizing state information of the computerreadable program instructions to personalize the electronic circuitry,in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

Reference in the specification to “one embodiment” or “an embodiment” ofthe present invention, as well as other variations thereof, means that aparticular feature, structure, characteristic, and so forth described inconnection with the embodiment is included in at least one embodiment ofthe present invention. Thus, the appearances of the phrase “in oneembodiment” or “in an embodiment”, as well any other variations,appearing in various places throughout the specification are notnecessarily all referring to the same embodiment.

It is to be appreciated that the use of any of the following “/”,“and/or”, and “at least one of”, for example, in the cases of “A/B”, “Aand/or B” and “at least one of A and B”, is intended to encompass theselection of the first listed option (A) only, or the selection of thesecond listed option (B) only, or the selection of both options (A andB). As a further example, in the cases of “A, B, and/or C” and “at leastone of A, B, and C”, such phrasing is intended to encompass theselection of the first listed option (A) only, or the selection of thesecond listed option (B) only, or the selection of the third listedoption (C) only, or the selection of the first and the second listedoptions (A and B) only, or the selection of the first and third listedoptions (A and C) only, or the selection of the second and third listedoptions (B and C) only, or the selection of all three options (A and Band C). This may be extended, as readily apparent by one of ordinaryskill in this and related arts, for as many items listed.

Having described preferred embodiments of a system and method (which areintended to be illustrative and not limiting), it is noted thatmodifications and variations can be made by persons skilled in the artin light of the above teachings. It is therefore to be understood thatchanges may be made in the particular embodiments disclosed which arewithin the scope of the invention as outlined by the appended claims.Having thus described aspects of the invention, with the details andparticularity required by the patent laws, what is claimed and desiredprotected by Letters Patent is set forth in the appended claims.

What is claimed is:
 1. A computer program product performing containersharing and scheduling in an environment having a plurality of contentconsuming nodes and a bypassable centralized container repository, thecomputer program product comprising a non-transitory computer readablestorage medium having program instructions embodied therewith, theprogram instructions executable by a computer to cause the computer toperform a method comprising: deploying a container management servicesystem that manages a list of layered images, the list of layered imagesspecifying one or more container attributes for each of the layeredimages stored at the plurality of content consuming nodes; selecting, bya processor-based scheduler of the container management system based onthe list of layered images, a given one of the plurality of contentconsuming nodes which (i) includes image layers residing in a containerand (ii) communicates with one or more candidate nodes that include oneor more missing image layers, wherein the one or more candidate nodesare determined from among the plurality of content consuming nodes basedon one or more availability criterion; and bypassing, using a clustermembership registry service of the container management service systemas an intermediary, wherein the cluster membership registry maintains alist of images downloaded from the plurality of content consumer nodes,the centralized container repository to satisfy a pull request bypulling the one or more missing image layers from the one or morecandidate nodes and copying the one or more missing image layers to thegiven one of the plurality of content consuming nodes, wherein saidpulling step comprises the one or more candidate nodes communicatingwith each other in order to satisfy the pull request.
 2. The computerprogram product of claim 1, wherein the method further comprisesupdating the list of layered images before launching a new container byany of the plurality of content consuming nodes.
 3. The computer programproduct of claim 1, wherein the method further comprises updating thelist of layered images before performing an image garbage collectioncycle on any of the plurality of content consuming nodes.
 4. Thecomputer program product of claim 1, wherein the one or more candidatenodes comprise two candidate nodes, the two candidate nodes comprising afirst candidate node and a second candidate node, wherein a given imagelayer from among the one or more missing image layers is missing fromthe first candidate node but present at the second candidate node, andwherein said pulling step provides a copy of the given image layer fromthe second candidate node to both the given one of the plurality ofcontent consuming nodes and the first candidate node by pulling thegiven image layer through the first candidate node to the given one ofthe plurality of content consuming nodes and storing the given imagelayer at the first candidate node and the given one of the plurality ofcontent consuming nodes.
 5. The computer program product of claim 1,wherein the one or more container attributes are selected from the groupconsisting of an image layer identifier, an image identifier, and a nodedistance.
 6. The computer program product of claim 1, wherein the one ormore availability criterion are selected from the group consisting ofCPU availability, communication bandwidth availability, and storageavailability.
 7. The computer program product of claim 1, wherein thelist of layered images comprises a respective unique identifier for eachimage layer of the layered images.
 8. The computer program product ofclaim 1, further comprising launching a new container by the given oneof the plurality of content consuming nodes by pulling the layeredimages for the new container from one or more other ones of theplurality of content consuming nodes.
 9. The computer program product ofclaim 8, wherein pulling the layered images for the new containercomprises bypassing a central repository that also includes copies ofthe layered images for the new container.
 10. The computer programproduct of claim 1, wherein the method further comprises registering adownloaded image list of each of the plurality of content consumingnodes with the container management service system.
 11. The computerprogram product of claim 1, wherein the environment is a cloudenvironment.
 12. The computer program product of claim 1, whereinsoftware for implementing the method is provided as a service in thecloud environment.
 13. The computer program product of claim 1, whereinthe list of images downloaded from the plurality of content consumernodes further includes container attributes.
 14. A system performingcontainer sharing and scheduling in an environment having a plurality ofcontent consuming nodes and a bypassable centralized containerrepository, the system comprising: a hardware-processor-based containermanagement service system having a hardware-based processor and memorydevice configured to: manage a list of layered images, the list oflayered images specifying one or more container attributes for each ofthe layered images stored at the plurality of content consuming nodes;select, based on the list of layered images, a given one of theplurality of content consuming nodes which (i) includes image layersresiding in a container and (ii) communicates with one or more candidatenodes that include one or more missing image layers, wherein the one ormore candidate nodes are determined from among the plurality of contentconsuming nodes based on one or more availability criterion; and bypass,using a cluster membership registry service of the container managementservice system as an intermediary, wherein the cluster membershipregistry maintains a list of images downloaded from the plurality ofcontent consumer nodes, the centralized container repository to satisfya pull request by pulling the one or more missing image layers from theone or more candidate nodes and copying the one or more missing imagelayers to the given one of the plurality of content consuming nodes,wherein said pulling comprises the one or more candidate nodescommunicating with each other in order to satisfy the pull request. 15.The system of claim 14, wherein the environment is a cloud environment.